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The adult sex ratio (ASR) has critical effects on behaviour, ecology and population dynamics (1,2), but the causes of variation in ASRs are unclear (3,4). Here we assess whether the [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2008.10.005 Byline: Zoltan Toth (a), Veronika Bokony (a), Adam Z. Lendvai (b), Krisztian Szabo (c), Zsolt Penzes (c)(d), Andras Liker (a) Abstract: Kin selection is often important in the evolution of reproductive behaviour, but we know much less about its significance for nonreproductive social groups. We investigated whether relatedness affects social-foraging behaviour in captive house sparrow, Passer domesticus, flocks, where birds may either search for food or exploit flockmates' food findings by scrounging. In such systems, both increased and decreased frequency of scrounging from relatives can be predicted by kin selection theory, depending on the relative costs and benefits of exploiting close kin. We found that birds used aggressive joining less often and obtained less food by that tactic from their close kin than from unrelated flockmates. In nonaggressive joinings, males also tended to join less often and obtained less food from close kin flockmates than from unrelated birds, whereas an opposite trend was found in females. Close kin males also spent less time feeding together from the same food patch than unrelated males, further suggesting reduced exploitation by male kin. These results suggest that house sparrows are able to recognize their close kin flockmates and reduce aggressive scrounging towards them, and that the sexes may differ in some forms of kin exploitation. Author Affiliation: (a) Department of Limnology, University of Pannonia, Hungary (b) Institute of Biology, College of Nyiregyhaza, Hungary (c) Institute of Genetics, HAS Biological Research Center, Szeged, Hungary (d) Department of Ecology, University of Szeged, Hungary Article History: Received 11 February 2008; Revised 8 April 2008; Accepted 2 October 2008 Article Note: (miscellaneous) MS. number: 08-00078R

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2005.10.032 Byline: Adam Z. Lendvai, Andras Liker, Zoltan Barta Abstract: In social animals, dominance rank often influences individuals' behaviour, but in most cases it is unknown how dominance modulates the effects of other phenotypic traits. We investigated the mutual effects of social dominance and the level of energy reserves on the use of social-foraging strategies in captive flocks of house sparrows, Passer domesticus. We used experimental wind exposure to manipulate overnight energy expenditure of dominant and subordinate individuals. In response to the experimental treatment dominants used scrounging (exploiting others' food finding) significantly more, whereas for subordinates there was only a moderate and nonsignificant increase in scrounging. Individual variability in the frequency of scrounging was higher in subordinates than in dominants and this difference between the dominance groups was unaffected by the treatment. These results suggest that individuals of different dominance status adopt different strategies: to cope with an energetically challenging situation, dominants behave rather uniformly by increasing further their preference for scrounging, whereas subordinates do not alter their tactic, but may rely on using scrounging opportunistically. Author Affiliation: (a) Department of Ethology, Eotvos University, Hungary (a ) Centre d'Etudes Biologiques de Chize, Centre National de la Recherche Scientifique, France (a ) Department of Limnology, Pannon University, Hungary (As.) Behavioural Ecology Research Group, Department of Evolutionary Zoology and Human Biology, University of Debrecen, Hungary Article History: Received 23 July 2005; Revised 24 August 2005; Accepted 29 October 2005 Article Note: (miscellaneous) MS. number: 8624R

A study was conducted on female lapwing aggressive behavior by introducing a female dummy conspecific and a male dummy within a lapwing's nest. Both dummies were attacked by female lapwings, with the female dummy lapwing receiving most of the ground and aerial assaults. Results reveal that the aggressiveness of the female lapwings is due to social monogamy and the preservation of the pair bond with their mates.

The effects of predation risk on the use of social foraging tactics by tree sparrows, Passer montanus, is studied experimentally. The result suggests that in tree sparrows, the increased predation risk is due to several mechanisms like stochasticity in food supply and risky sites used by individuals possessing low reserves.